Connecting 3 wire to a 4 wire service panel

Asked Nov 6, 2006, 10:10 AM
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5 Answers

I am trying to connect from a 3 wire system at the utility pole to a 4 wire service panel inside a new mobile home. I called an electrician for some advice and was told that I needed to drive an 8ft ground stake and attach a solid copper wire from the stake to the ground bar in the panel. Then I would need to wire a jumper from the neutral bar over to the ground bar in the panel. Does this sound like I was given good advice? If not any help you can give would be appreciated. Thanks

Before we can answer with any certainty, the key piece of inforamtion is missing, where is the main breaker located, at the utility pole with the meter, or in the panel in the house?

The ground rod(s),(you may need two) need to connect to the main neutral bar located at the main breaker/disconnect. If at the meter/disconnect, then the line and load neutrals connect along with the wire to the ground rod, and the fourth wire going to the panel, and a jumper at this connection to the box containing the main.

With the main disconnect outside at the meter pole, the neutral in the panel is isolated, and the fourth wire connects to the equipment ground bar, which is bolted directly to the panel box.

If the main is in the panel, then this is where the neutral gets grounded, and the advice you received is correct.

Thanks for the quick response. This meter loop connects to a 200 amp service panel in mobile home... Please forgive me if I get some of the technical names wrong... here it is, from the pole to the mobile home, 3-wire supply at utility pole to meter. There is a #6 copper wire from meter box to ground stake at base of pole. Outdoor 100amp service disconect directly below meter box on pole(3wires in 3wires out). 3-wires run 60 ft. underground in conduit and sweep up into mobile home wall to a 200 amp (4-wire) service panel. My problem is, how do I connect safely to this panel? Can I connect the 3-wires to hot, hot, neutral and then ADD/CONNECT to the ground bar in the panel a #6 copper wire and drive a new ground stake just outside of the trailer? If so, do I then add a small jumper wire inside the panel from the ground bar to the neutral bar? Thanks again for your helpful advice, Deanmachine

Since the 100 amp meter AND disconnect is at the pole, 4 wire cable should be from the pole to the house panel. At the main is where the grounding begins, the ground rod #6 connecting to the neutral bar in the main, along with the feed neutral, from the utility, the load neutral, going to the house panel, and the missing fourth wire , which should be a smaller bare or insulated wire intended to be the equipment ground.

Does the house panel have a main breaker in it? By the way, even if it is a 200 amp panel, with a 200 amp main, it is limited to 100 amp due to the 100 amp main breaker at the pole.

If there is no way to get a fourth wire from the pole disconnect to the house panel, then:

If there is a main breaker at the panel, I would move the rod to the house and ground the neutral and equipment ground bar there.

If there is no main breaker at the house, I would install a 100 amp breaker in the branch slots to backfeed the panel, creating a main, this breaker needs a retaining kit, since it is now a main breaker, and again proceed to install ground rods at the house, and ground as I already explained.

Once there is a main and rods at the house, you can leave the main out at the pole, but must disconnect the ground rod there.

This assumes the ground wire does connect to the main breaker box at the pole. If the rod wire bypasses the main and meter , and continues up the pole to the utility, then do not disconnect it, but continue to ground at the house panel as I explained.

Is your head spinning yet?

Why a 100 amp service for a home that came with a 200 amp panel, which usually means the house needs a 200 amp panel & service?

By the way, if you end up grounding at the house panel, with a main in it, the neutral bar needs to be bonded to the equipment ground, usually with a long green screw through the neutral bar into the metal backbox of the panel, or a small jumper from bar to box.

What exactly are you asking?? There is no "conversion". A mobile home requires an outside disconnect and a 4-wire feeder to the trailer. The disconnect is fed with a standard "3-wire" service and the neutral is bonded at this disconnect.

You question leaves out many details. Can you describe a little better what it is you want to know?

Add your answer here.

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